The present invention relates generally to pulse radar systems and, more particularly, to producing multiple radar maps at the same time using a pulse radar system having a single antenna.
Surveillance is frequently conducted using pulse radar systems. For example, ground, airborne and satellite-based pulse radar systems are commonly employed for detecting and tracking aircraft, and for mapping and tracking ground targets.
In a conventional pulse radar system, a single radar pulse is transmitted toward a target. The system then waits to receive a return signal for producing a radar map of the target. In order to improve the signal-to-noise ratio of radar maps, multiple return signals from the same target can be combined (e.g., integrated). However, the system timing must be such that a new radar pulse is unambiguous, i.e., not transmitted prior to receiving the return signal from the prior radar pulse, plus an additional wait period to avoid ambiguities (e.g., multiple-time-around echoes) which could otherwise distort the radar map. This transmit and receive timing is shown generally in FIG. 1, which illustrates how the transmit and receive times together account for only a small percentage of the total available timeline.
Certain improvements have been proposed to more efficiently use the available timeline of conventional pulse radar systems. For example, the inventor hereof previously developed a radar system in which multiple radar waveforms operating at different non-interfering frequencies were time-interleaved and transmitted by the same radar antenna so as to reduce the time required for generating a high signal-to-noise ratio map of a single target. However, this and other known systems are limited in the sense that only a single target or region can be mapped at any given time.
The inventor hereof has succeeded at designing a pulse radar system capable of mapping multiple targets essentially simultaneously using a single radar antenna. By alternately transmitting radar pulses toward multiple targets positioned at different angles relative to the antenna and alternately receiving return signals from the multiple targets as the radar antenna is switched between multiple beam positions, a time-interleaved radar operation is achieved which enables multiples targets to be mapped, and thus tracked, at the same time. In one preferred form of the invention, a different radio frequency is employed for each target so as to avoid interference and ambiguous returns. Using the teachings of the present invention, between two and twenty radar maps, and possibly more, can be generated simultaneously in approximately the same amount of time required to map a single target using conventional systems of the prior art.
According to one aspect of the invention, a method of conducting radar includes transmitting a radar pulse toward a first region using a radar antenna, switching a beam position of the radar antenna from the first region to a second region, transmitting a radar pulse toward the second region, switching the beam position from the second region to the first region, receiving a return signal from the first region, switching the beam position from the first region to the second region, receiving a return signal from the second region, and producing a radar map of the first region and a radar map of the second region using said return signals.
According to another aspect of the invention, a pulse radar system includes an electronically scanned antenna and a computer for controlling switching of the antenna between multiple beam positions. The system is configured to a alternately transmit radar pulse s toward multiple targets positioned at different angles relative to the antenna and to alternately receive return signals from the multiple targets as the antenna is switched between the multiple be am positions, and to generate radar maps of the multiple targets using the return signals.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limited the scope of the invention.